An airplane used to drop water on brushfires is flying horizontally in a straight line at 180 mi/h at an altitude of 390 ft. Determine the distance d at which the pilot should release the water so that it will hit the fire at B.

The water should be released a distance of 1289.88 feet before the plane is on top of the bush fire.

Explanation:

Let's first find the time required for the water to fall down 390 ft onto the bush fire.

Initial Vertical Speed of water = 0

Distance to be covered = 390 ft

Acceleration due to gravity = 32.2 ft/s^2

t = 4.92 seconds

Thus the water should be dropped 4.92 seconds before the plane is over the bush fire. Now we can also find the distance d at which the pilot should release the water:

d = Speed of plane * time

Speed of plane = 180 / (60 * 60) = 0.05 mile/second

d = 0.05 * 4.92 = 0.246 miles    OR    1289.88 feet

Thus, the water should be released a distance of 1289.88 feet before the plane is on top of the bush fire.

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